Smoking potent cannabis was linked to 24% of new psychosis cases analysed in a study by King’s College London. The research suggests the risk of psychosis is three times higher for users of potent “skunk-like” cannabis than for non-users. The study of 780 people was carried out by KCL’s Institute of Psychiatry, Psychology and Neuroscience. A Home Office spokesman said the report underlines the reasons why cannabis is illegal.

Scientists found the risk of psychosis was five times higher for those who use it every day compared with non-users. They also concluded the use of hash, a milder form of the drug, was not associated with increased risk of psychosis.

Psychosis refers to delusions or hallucinations that can be present in certain psychiatric conditions such as schizophrenia and bipolar disorder. “Compared with those who had never tried cannabis, users of high potency skunk-like cannabis had a threefold increase in risk of psychosis,’ said Dr Marta Di Forti, lead author on the research.

She added: “The results show that psychosis risk in cannabis users depends on both the frequency of use and cannabis potency.”

Cath from Berkshire, who asked to remain anonymous, believes smoking skunk caused her to experience mental health problems. “I dabbled with a friends’ group in my early 20s, and went from someone who had never experienced any mental health issues whatsoever, to an absolute wreck. “I was terrified of leaving the house, and I became petrified of death, of the mysteries of the universe, and of being alone. You name it, I was terrified of it. “It took about six years to feel normal again and now, almost 20 years later, I have absolutely no doubt that my issues were triggered by casually and naively smoking this so called ‘soft’ drug.